1,399 research outputs found
The associations of adipokines with selected markers of the renin-angiotensinogen-aldosterone system: the multi-ethnic study of atherosclerosis.
Among obese individuals, increased sympathetic nervous system (SNS) activity results in increased renin and aldosterone production, as well as renal tubular sodium reabsorption. This study determined the associations between adipokines and selected measures of the renin-angiotensinogen-aldosterone system (RAAS). The sample consisted of 1970 men and women from the Multi-Ethnic Study of Atherosclerosis who were free of clinical cardiovascular disease at baseline and had blood assayed for adiponectin, leptin, plasma renin activity (PRA) and aldosterone. The mean age was 64.7 years and 50% were female. The mean (s.d.) PRA and aldosterone were 1.45 (0.56) ng ml(-1) and 150.1 (130.5) pg ml(-1), respectively. After multivariable adjustment, a 1-s.d. increment of leptin was associated with a 0.55 ng ml(-1) higher PRA and 8.4 pg ml(-1) higher aldosterone (P<0.01 for both). Although adiponectin was not significantly associated with PRA levels, the same increment in this adipokine was associated with lower aldosterone levels (-5.5 pg ml(-1), P=0.01). Notably, the associations between aldosterone and both leptin and adiponectin were not materially changed with additional adjustment for PRA. Exclusion of those taking antihypertensive medications modestly attenuated the associations. The associations between leptin and both PRA and aldosterone were not different by gender but were significantly stronger among non-Hispanic Whites and Chinese Americans than African and Hispanic Americans (P<0.01). The findings suggest that both adiponectin and leptin may be relevant to blood pressure regulation via the RAAS, in that the associations appear to be robust to antihypertension medication use and that the associations are likely different by ethnicity
Prioritized Sweeping Neural DynaQ with Multiple Predecessors, and Hippocampal Replays
During sleep and awake rest, the hippocampus replays sequences of place cells
that have been activated during prior experiences. These have been interpreted
as a memory consolidation process, but recent results suggest a possible
interpretation in terms of reinforcement learning. The Dyna reinforcement
learning algorithms use off-line replays to improve learning. Under limited
replay budget, a prioritized sweeping approach, which requires a model of the
transitions to the predecessors, can be used to improve performance. We
investigate whether such algorithms can explain the experimentally observed
replays. We propose a neural network version of prioritized sweeping
Q-learning, for which we developed a growing multiple expert algorithm, able to
cope with multiple predecessors. The resulting architecture is able to improve
the learning of simulated agents confronted to a navigation task. We predict
that, in animals, learning the world model should occur during rest periods,
and that the corresponding replays should be shuffled.Comment: Living Machines 2018 (Paris, France
The J-triplet Cooper pairing with magnetic dipolar interactions
Recently, cold atomic Fermi gases with the large magnetic dipolar interaction
have been laser cooled down to quantum degeneracy. Different from
electric-dipoles which are classic vectors, atomic magnetic dipoles are
quantum-mechanical matrix operators proportional to the hyperfine-spin of
atoms, thus provide rich opportunities to investigate exotic many-body physics.
Furthermore, unlike anisotropic electric dipolar gases, unpolarized magnetic
dipolar systems are isotropic under simultaneous spin-orbit rotation. These
features give rise to a robust mechanism for a novel pairing symmetry: orbital
p-wave (L=1) spin triplet (S=1) pairing with total angular momentum of the
Cooper pair J=1. This pairing is markedly different from both the He-B
phase in which J=0 and the He- phase in which is not conserved. It
is also different from the p-wave pairing in the single-component electric
dipolar systems in which the spin degree of freedom is frozen
Recommended from our members
Letter processing and font information during reading: beyond distinctiveness, where vision meets design
Letter identification is a critical front end of the
reading process. In general, conceptualizations of the identification process have emphasized arbitrary sets of distinctive features. However, a richer view of letter processing incorporates principles from the field of type design, including an emphasis on uniformities across letters within a font. The importance of uniformities is supported by a small body of research indicating that consistency of font increases letter identification efficiency. We review design concepts and the relevant literature, with the goal of stimulating further thinking about letter processing during reading
The mechanisms of feature inheritance as predicted by a systems-level model of visual attention and decision making
Feature inheritance provides evidence that properties of an invisible target
stimulus can be attached to a following mask. We apply a systemslevel model of
attention and decision making to explore the influence of memory and feedback
connections in feature inheritance. We find that the presence of feedback loops
alone is sufficient to account for feature inheritance. Although our simulations
do not cover all experimental variations and focus only on the general
principle, our result appears of specific interest since the model was designed
for a completely different purpose than to explain feature inheritance. We
suggest that feedback is an important property in visual perception and provide
a description of its mechanism and its role in perception
Infection-dependent phenotypes in MHC-congenic mice are not due to MHC: can we trust congenic animals?
BACKGROUND: Congenic strains of mice are assumed to differ only at a single gene or region of the genome. These mice have great importance in evaluating the function of genes. However, their utility depends on the maintenance of this true congenic nature. Although, accumulating evidence suggests that congenic strains suffer genetic divergence that could compromise interpretation of experimental results, this problem is usually ignored. During coinfection studies with Salmonella typhimurium and Theiler's murine encephalomyelitis virus (TMEV) in major histocompatibility complex (MHC)-congenic mice, we conducted the proper F(2 )controls and discovered significant differences between these F(2 )animals and MHC-genotype-matched P(0 )and F(1 )animals in weight gain and pathogen load. To systematically evaluate the apparent non-MHC differences in these mice, we infected all three generations (P(0), F(1 )and F(2)) for 5 MHC genotypes (b/b, b/q and q/q as well as d/d, d/q, and q/q) with Salmonella and TMEV. RESULTS: Infected P(0 )MHC q/q congenic homozygotes lost significantly more weight (p = 0.02) and had significantly higher Salmonella (p < 0.01) and TMEV (p = 0.02) titers than the infected F(2 )q/q homozygotes. Neither weight nor pathogen load differences were present in sham-infected controls. CONCLUSIONS: These data suggest that these strains differ for genes other than those in the MHC congenic region. The most likely explanation is that deleterious recessive mutations affecting response to infection have accumulated in the more than 40 years that this B10.Q-H-2(q )MHC-congenic strain has been separated from its B10-H-2(b )parental strain. During typical experiments with congenic strains, the phenotypes of these accumulated mutations will be falsely ascribed to the congenic gene(s). This problem likely affects any strains separated for appreciable time and while usually ignored, can be avoided with the use of F(2 )segregants
Masses of high-z galaxy hosting haloes from angular clustering and their evolution in the CDM model
We examine masses of hosting haloes of two photometrically-selected high-z
galaxy samples: the old passively-evolving galaxies (OPEGs) and Lyman Break
Galaxies (LBGs) both taken from the Subaru/XMM-Newton Deep Survey (SXDS). The
large survey area of the SXDS (1sq deg) allows us to measure the angular
two-point correlation functions to a wide separation of >10 arcmin with a good
statistical quality. We utilize the halo model prescription for estimating
characteristic masses of hosting haloes from the measured large-scale
clustering amplitudes. It is found that the hosting halo mass positively
correlates with the luminosity of galaxies. Then, adopting the extended
Press-Schechter model (EPS), we compute the predictions for the mass evolution
of the hosting haloes in the framework of the cold dark matter (CDM) cosmology
in order to make an evolutionary link between the two galaxy samples at
different redshifts and to identify their present-day descendants by letting
their haloes evolve forward in time. It is found that, in the view of the mass
evolution of hosting haloes in the CDM model, bright LBGs are consistent with
being the progenitor of the OPEGs, whereas it is less likely that the LBG
population, as a whole, have evolved into the OPEG population. It is also found
that the present-day descendants of both the bright LBGs and OPEGs are likely
to be located in massive systems such as groups of galaxies or clusters of
galaxies. Finally, we estimate the hosting halo mass of local early-type galaxy
samples from the 2dF and SDSS based on the halo model and it turns out that
their expected characteristic mass of hosting haloes is in good agreement with
the EPS predictions for the descendant's mass of both the bright LBGs and
OPEGs.Comment: 10 pages, 10 figures, submitted to MNRAS. Fortran programs used to
compute the model predictions in this paper are available at
http://optik2.mtk.nao.ac.jp/~hamanatk/OPENPRO/index.htm
Combining perturbation theories with halo models for the matter bispectrum
We investigate how unified models should be built to be able to predict the
matter-density bispectrum (and power spectrum) from very large to small scales
and that are at the same time consistent with perturbation theory at low
and with halo models at high . We use a Lagrangian framework to decompose
the bispectrum into "3-halo", "2-halo", and "1-halo" contributions, related to
"perturbative" and "non-perturbative" terms. We describe a simple
implementation of this approach and present a detailed comparison with
numerical simulations. We show that the 1-halo and 2-halo contributions contain
counterterms that ensure their decay at low , as required by physical
constraints, and allow a better match to simulations. Contrary to the power
spectrum, the standard 1-loop perturbation theory can be used for the
perturbative 3-halo contribution because it does not grow too fast at high .
Moreover, it is much simpler and more accurate than two resummation schemes
investigated in this paper. We obtain a good agreement with numerical
simulations on both large and small scales, but the transition scales are
poorly described by the simplest implementation. This cannot be amended by
simple modifications to the halo parameters, but we show how it can be
corrected for the power spectrum and the bispectrum through a simple
interpolation scheme that is restricted to this intermediate regime. Then, we
reach an accuracy on the order of 10% on mildly and highly nonlinear scales,
while an accuracy on the order of 1% is obtained on larger weakly nonlinear
scales. This also holds for the real-space two-point correlation function.Comment: 25 page
- …